Coal nozzle assembly for a steam generation apparatus

A method comprising:

• implementing a coal nozzle assembly in a steam generation apparatus, the coal nozzle assembly including:
• an inner housing for conveying primary air and coal particles through a nozzle tip toward an exit face;
• an outer housing for conveying secondary air through the nozzle tip,
• at least one bar located in the inner housing near the exit face;
• and
• a cover plate downstream of the at least one bar to prevent abrasion of the trailing edges of the at least one bar,
• wherein the outer housing and the inner housing are arranged coaxially and limit a channel for the secondary air,
• wherein the cross-sectional area (AIH) of the inner housing increases towards an exit face of the nozzle tip,
• wherein the cross-sectional area (AOH) of the outer housing decreases towards the exit face;
• and
• operating the coal nozzle assembly to convey the primary air and the coal particles through the inner housing toward the exit face and to convey the secondary air through the outer housing, wherein the operating includes:
• decelerating the flow of the primary air and the coal particles;
• subsequently accelerating the flow of primary air and the coal particles;
• mixing the flow of primary air and the coal particles by inducing a stall when exiting the inner housing;
• and
• enclosing the primary air and the coal particles by a perimeter flow of the secondary air.

A steam generating system, comprising:

• a furnace;
• and
• a coal nozzle assembly for directing a flow of solid particles entrained in a fluid into the furnace, wherein the coal nozzle assembly includes:
• a nozzle tip;
• an inner housing for conveying primary air and coal through the nozzle tip toward an exit face;
• an outer housing for conveying secondary air through the nozzle tip,
• at least one bar located in the inner housing near the exit face;
• and
• a cover plate downstream of the at least one bar to prevent abrasion of the trailing edges of the at least one bar,
• wherein the outer housing and the inner housing are arranged coaxially and limit a channel for the secondary air,
• wherein the cross-sectional area (AIH) of the inner housing increases towards an exit face of the nozzle tip, and
• wherein the cross-sectional area (AOH) of the outer housing decreases towards the exit face.